Elastic-fluid turbine.



No. 850,397. PATENTBD" APR. 1e, 1907.

H. P. R. L. PRSCKE.

ELASTIG FLUID TURBINIL APPLIUATION FILED 00T.12. 1906.

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No. 850,397. I v PATENTED APR. 16, 1907. H. P. R. L. PRSGKE.

ELA D TURBINE.

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UNITED sTATEs PATENT OFFICE.

ELASTlC-FLUID TURBINE.

Specification of Letters Patent.

Patented April 16, 1907.

Application filed October 12,1906. Serial N0 338,612.

e y DOLF LUDWIG PRsCKE, a subject of the German Emperor, residing atHamburg, in Ger- 'many, have invented certain new and-usefulImprovements in Elastic-Fluid Turbines, of which the following is aspecification.

This invention relates to improvements in elastic-Huid turbines.

I In the steam-turbines of known constructionin which the velocity of asteam-j et fiowing into the free atmosphere is used in such a mannerthat high-pressure steam impinges on the vanes of a wheel after beingfully eX- panded and transfers its @is viva to said blades to rotate thewheel a high linear velocityof the wheel is conditional upon the highvelocity of exhaust. This high linear velocity of the wheel requireseither the application of gearing as in the De Laval turbine or theuseof. wheels of large diameter, as in the Riedler-Stumpf type, in orderto attain the useful number of revolutions for practical working. Theinconveniences thus arising are very evident in the construction of theDe Laval type, the high gearing causing a large portion of the energy tobe absorbed by friction, whereas in the Riedler-Stumpf construction thelarge wheels must be very accurately balanced in order to obviate thedangerous effects of centrifugal force andthe losses by frictionAresulting therefrom. Moreover, the large dimensions and considerablemass which absorbs energy are further disadvantages, and, again, in bothconstructions the @is @im of the steam is not completely utilized. In anumber of American and English constructions a better utilization ofsteam has been attained by passing the steam several times throughhelical or loopshaped channels back to the vanes of the wheel. The steamis, however, not used completely, since on entering the turbine thesteam-jet, having still a certain tension and a considerable velocityimpinging against a few vanes of the wheel, increases in volume onleaving said vanes and is passed back several times to the wheel throughhelical or loop-shaped channels of equal cross-section and pitch or nheight. The inconvenience arising therefrom is that the steam-jet whichincreases in volume during the work is subjected to friction in saidchannels of equal cross-section, and this is greater the larger thenumber of channels to be traversed.

`Throttling ,of the steam-jet therefore takes place, whereby itsvelocity is considerably reduced and probably so much so that on thesecond or third return to the vanes such velocity is already reduced tobelow that proportional to the peripheral speed of the wheel,andtherefore has a braking effect. Even if the channels are made of suchlarge cross-section that the steam-jet at first occupies, for instance,only a quarter thereof, so that throttling would eventually be obviated,the velocity of the et would be reduced, owing to progressive expansion,in such a manner that after a few returns to the vanes the velocitywould still be below that required by the peripheral speed of the Wheel.Since in the aforesaid constructions a repeated return of the steam-jetto the blades is required for `completely utilizing the steam, owing tothe shallow pitch of the channels and. vanes, these constructions arenot successful.

In the construction of turbine according to the present invention allthe'aforesaid disadvantages are removed.`v The effect of the steam-viz.,its bis @ita-is completely utilized in spite of repeated returns of thesame steam-jet to the vanes without appreciable frictional loss in thechannels, this being obtained by causing the steam-jet on entering thevanes to first impinge upon the vanes at a small angle to the axis,(small pitch of the leading channels,)` and this angle increasesprogressively at each further return to the vanes, the pitch of thechannels increasing in proportion to the decreasing speed of the steam.Simultaneously with the increasing pitch of the channels at each returnof the steam-jet the cross-section of the channels increases inproportion to the pitch and according to the progressive expansion ofthe steam, so that with the progressive enlargement of the `angle ofimpact a continually-increasing number of wheel-vanes are acted upon.With this repeated effective return of the steam-jet, in whichmanywheel-vanes are acted upon simultaneously by the steam, the numberof revolutions of the turbineshaft is comparatively small, the wheel isbalanced, owing to impact on both sides, and the turbine may be madelreversible. A great advantage incomparison with known constructionsconsists in the fact that during the whole work from inlet to exhaustthe steam is completely utilized in spite of the repeated return of thesteam-j et to the blades. Assuming twenty gradations of pressure andvelocity, (with ten screw-channels,) the IOS IIO

practically expanded steam-jet retarded in its speed still delivers acertain force to the wheel. As from the beginning of the vfirstpressure-degree down to the last gradationthat is to say, the twentiethacontinuous decrease in the number of screw-channels per At impact No.15,

At impact No. l0= 30,

At impact No.y 20:60", and the absolute speed be,

At impact No. 1 =800 m. per second, At impact No. 10:41:00 m. persecond, At impact No. 20: 900 m. per second,

the resultant peripheral speeds without regarding loss from bearingfriction are as follows:

For impact No. l-

O 6995661? 133.3 m. per Second For impact No. lO-O 4% O3 0 13g-3 3 m.per second,

For impact No. 20e-O 2209?@ 133.3 m. per second.

It will be seen the live-steam jet first entering the turbine at highspeed propels the wheel at no greater number of revolutions than thefully-expanded steam-jet at the `last gradation of pressure and retardedin its velocity by the previous delivery. At the firstimpact the wheelis acted upon by a livesteam jet of small volume and small angle to aline parallel to the axis, the vane-surface being large, but number ofthe vanes acted upon small. At the last impact, however, the wheel isacted upon by a fully-expanded steam-jet of large volume at a largeangle to a line parallel to the wheel-axis, the vanesurface being small,but the number of vanes acted upon being large.

Reference being made to the annexed drawings, Figure l is a view,principally in section in the line of the axis, of a form of turbinewith one circular helical steam-passage. Fig. 2 is a view of one-half ofthe casing. Fig. 3 shows part of the wheel. Fig. 4 is a diagram of thehelical passage of the vanes and illustrates the increasing pitch andsteam is illustrated through onev passage. Fig. 7 is an axial section,Fig. 8 a side or end of the wheel, and the upper right-hand quarp ter adiagram in which the course of the view, and Fig. 9 a diagramillustrative of anp other modification.

ln the form of construction illustrated in stance, at d#at an angle offifteen degrees to a line parallel to the axis. At or about the centerthe pitch of the screw-channels has increased so far that the jet actson the vane-for example, at ZX-at an angle of thirty degrees to a lineparallel to the axis, and from the center to the end at dy the pitch ofthe screw-channels has continuously increased, so that at the lastconvolution the jet acts on the vane at an angle of about sixty degreesto a line parallel to the axis. With the continually-increasing pitch ofthe screw-channels the cross-section of the latter also increases. Ifsaid cross-section at the IOO commencement at d is thirty squaremillimeters, that shortly before the outlet toward dy would be onehundred and twenty square millimeters. The core of the helical channelsis formed by the wheel, which is provided at the top and bottom of thehelix with straight vanes e c or vanes having opposite inclination atthe outer circular group 'e to those at the inner group c. The vanes cform at the same time the connection with the parts w and o of theactual wheel-body, and the upper vane-crown e is surrounded by aclosing-ring z. The vanes of both groups c and c must therefore be ofopposite angle of inclination to each other in order that the l steamacts on both sets of vanes in uniform manner to produce rotation. Owingto the helical shape of the guide-channels d d, the the inner vane groupc is acted upon, for instance, from the left, Fig. 1, and the outergroup e from the right, whereby the wheel rotates in the casing withoutaxial thrust. The operation of this form of turbine is as follows: Thesteam enters through a three- Way cock a, whence it is directed into apipefor instance, for forward motion-and acts as a jet of small volumeand at a small angle to a line parallel to the axis on the inner groupof vanes c. After having acted upon one or more vanes, and thus imparteda cer- IOS tain amount of energy in the form of rotation to the wheel,it enters at the opposite side a guide-channel d, the inlet of which isenlarged and the outlet narrowed. This guide-channel has already asomewhat increased pitch, so that the et acts on the outer vane group cat an angle of about seventeen degrees to` a line parallel to the axis.The steam-jet then acts at each convolution upon the inner vane groupfrom the left, Fig; 7, and on the upper vane group from the right. Fromthe inlet to the outlet the steam-j et increases in volume anddecreasesin pressure at eachconvolution, always acting on more vanes thanpreviously. At the same time the helical passage of the steamprogressively increases in pitch.

1 If the above-described turbine is to be reversible, the steamisdirected by operating the three-way cock to,` communicate withscrew-guides g of opposite pitch to those `for forward` direction. Ifthe impact-angles of the forward guide are regarded as "plus vdegrees tothe axis, the impact-angles for reversal will be minus degrees to theaxis, and therefore opposite. The action of the steam-jet is exactly thesame as for forward driving with the exception that the wheel rotates inthe reverse direction. The steam exhausts at f.

Several guide-channels may be arranged in a casing' with cross-sectionincreasing at every return and also with increase of impact-angles to aline parallel to the axis for forward driving and` also severalguide-channels, as aforesaid, for reversing.

In the modification shown in Figs. 5 and three helical channels areshown supported radially above one another, and said channels areintersected through by the wheel, the vane groups of which increase, forinstance, in three degrees of width of vanes. In this construction thelive steam from c enters a ring-shaped steam-space b, whence it passesthrough orifices controlled by needle-valves to the outermost vane group1 of the wheel and from the latter through several guidechannels d d,which increase in cross-section and pitch at every half-convolution, thesteam in its passage acting upon the first and second vane groups l and2 of the wheel. The steam then passes through a transmis sion-channel e,which directs it at a somewhat larger angle to a line parallel to theaxis against the third vane group 3. The steam now acts during itshelical course through one or more channelsf of increasing pitch andcross-section on the third and fourth groups of vanes 3 and 4 and thenpasses in still larger volume and at a larger angle of pitch through asecond transmission-channel g to the fifth group of vanes 5, whereuponit passes through one or more channels h of the largest cross-sectionand of somewhat greater pitch than the preceding ones and impinges onits way upon the fifthand sixth groups of vanes 5 and 6, Yfinallyentering an exhaust channelor chamber. The Width of the sin gle groupsof vanes increases with their decreasing diameter in order toapproximately balance the smaller leverage of the groups of smaller.diameter by a larger pressure effect on the single'vanes. In thisconstruction the steam-jetv of greatest velocity and pressure, butofsmallest volume enters helical channels of smallest cross-section andacts'upon the first andrsecond groups of vanes of high .rotationalspeed, butlhaving smallvane-surfaces, and delivers a part of its forcein the form of rotation.` The steam-jet then enters helicalguide-channels oflarger cross-section in order to allow of the increase'of volume of the steam, owing to expansion, then acting on fact thatwithincrease of screw pitch and decrease of steam-pressure the surfaces ofthe vanes actedupon by the steam-jet considerably increase. This isobtained by causing the `diameters of the helical channels toproressively increase, for instance, in three degrecs and at the sametime successively increasing the width ofthe Wheels which intersectsaidchannels. By these means a vanesurface considerably increasing inthree degrees of pressure is offered to the steam-jet, which expandsduring its work, and at the same time the impact angle progressivelyincreases from the entrance of steam to the exhaust thereof. For forwarddriving the steam is caused to enter one preliminary steam-chamber o andfor backward driving another chamber p and passes from the one or otherof said chambers through the helical guide-channels which successivelyincrease in cross-section and pitch. The steam thus acts on the wheels,the vanes of which increase in width from the first wheel 7c to the lastwheel m. From said last wheel the lsteam enters an exhaust-collectingchannel or chamber u.

What I claim as my invention, and desire to secure by Letters Patent ofthe United States, is-

1. In a turbine the combination of a casing containing helical passagesincreasing progressively in pitch and in cross-sectional area, andhaving their axes disposed in circles about the axis of.said casing saidcasing having also a chamber extending from the axis of the casing andintersecting the said helical passages on two sides in the plane of adiam- IOO' eter thereof, and a wheel j ournaled axially in naled axiallyin said casing extending with said casing extending with said chamberand having vane-crowns where said wheel intersects the helical passages.

2. In a turbine the combination of a casing containing a plurality ofhelical passages increasing progressively in pitch and in crosssectionalarea, and having their axes disposed in circles about the axis of saidcasing said casing having also a chamber extending from the axis of thecasing and intersecting the said helical passages on two sides in theplane of a diameter thereof, a wheel journaled axially in said casingextending with said chamber and having vane crowns where said wheelintersects the helical passages, andv means for controlling theadmission of expansive fluid to said passages.

3. In a turbine the combination of a casing containing a plurality ofhelical passages opposite in helical direction and increasingprogressively in pitch and in cross-sectional area, and having theiraxes disposed in circles about the axis of said casing said casinghaving also a chamber extending from the axis of the casing andintersecting the said helical passages on two sides in the plane of adiameter thereof, a wheel j ournaled axially in said casing extendingwith said chamber and having vane-crowns where said wheel intersects thehelical passages, and means for controlling the admission of expansivefluid to said passages respectively.

4. In a turbine the combination of a casing containing a plurality ofhelical passages increasing progressively in pitch and in crosssectionalarea, and having their axes disposed in circles about the axis of saidcasing said casing having also a chamber extending from the axis of thecasing and intersecting the said helical passages on two sides in theplane of a diameter thereof, a wheel joursaid chamber and having aplurality of vanecrowns where said wheel intersects the helicalpassages, means for passage of the expansive iiuid from one helicalpassage to another in series, and means for controlling the admission ofexpansive fluid to said passages.

5. In a turbine the combination of a casing containing helical passagesincreasing progressively in pitch and in cross-sectional area, andhaving their axes disposed in circles about the axis of said casing saidcasing having also a chamber extending from the axis of the casing andintersecting the said helical passages on two sides in the plane of adiameter thereof, a wheel journaled axially in said casing extendingwith said chamber and having vane-crowns where said wheel intersects thehelical passages, the vanes of said vane-crowns being obliquely directedto the plane of intersection of the helical passage, those of one crownbeing oppositely directed to those of the other crown, and means forcontrolling the admission of expansive fluid to said passages.

6. In a turbine, the combination, with a revoluble wheel having an innerand an outer series of vanes at its periphery, of a casing provided withsegmental passages arranged in helical form at the opposite sides of thesaid wheeland with a progressively-increasing pitch and operating toconduct the motor iiuid from the vanes of one series to the vanes of theother series continuously and in a helical path.

In witness whereof I have signed this speciiication in the presence oftwo witnesses.

IVI. I. RUDOLF L. PRSCKE.

Witnesses:

SIEGFRIED SToRci-i, OTTO W. IIELLMRIGH.

